The crops are BT corn, which have toxins spliced into their DNA so that certain insects die upon eating them. Currently, BT corn accounts for about 57 percent of domestic corn acreage.

The concern is that the bugs could eventually grow resistant to the toxins genetically modified into the corn. And, since all the corn is the same, one set of BT corn-resistant bugs could easily wipe out an entire crop, or even the entire industry BT crop industry.

This is a concern with other genetically modified fruits and vegetables, such as Cavendish bananas ­— pretty much the only type of bananas seen in U.S. markets — which are vulnerable to a fungus or bacterial disease that could easily destroy millions of identical bananas, reported MNN blogger Siel Ju in March.

“After 15,000 years of human cultivation, the banana is too perfect, lacking the genetic diversity that is key to species health. What can ail one banana can ail all. A fungus or bacterial disease that infects one plantation could march around the globe and destroy millions of bunches, leaving supermarket shelves empty," writes Dan Koeppel, author of Banana: The Fate of the Fruit that Changed the World, in a Popular Science article.

To keep this from happening to the entire U.S. crop of genetically modified corn, the EPA requires that farmers in the Corn Belt plant 20 percent of their fields with non-BT corn as a sort of refuge for insects.

The idea is that even if some bugs do become resistant to the BT corn, they’re likely to mate with a non-resistant insect from the refuge, and therefore their offspring would not be resistant. But, this also means that farmers are essentially "eating" 20 percent of their crop every year by giving it up to ravenous bugs.

Not surprisingly, many farmers have decided to skirt the rules by not planting the non-BT corn, which has the unfortunately effect of potentially increasing the risk of a rising population of resistant bugs.

The noncompliance also doesn’t reflect well on the EPA’s or the agricultural biotech industry’s ability to enforce the rules.

The data “should be a wake-up call to E.P.A. that the regulatory system is not working,” wrote Gregory Jaffe, the biotechnology project director at the Center, in a letter Thursday to Lisa P. Jackson, the administrator of the federal agency.

So far, the EPA hasn’t made any comments concerning the issue, saying only that it will evaluate the report and take action if necessary.

Meanwhile, the four biotechnology giants — Monsanto, Pioneer Hi-Bred, Syngenta, and Dow AgroSciences — have been sending out postcards as part of their “Respect the Refuge” campaign and putting billboards alongside highways in the Corn Belt in an effort to encourage compliance.

“We’re not happy to see negative trends,” said Nicholas Storer, chairman of Agricultural Biotechnology Stewardship Technical Committee, to the Times.